The present invention is directed toward an air spring. More specifically, the present invention is directed towards an air spring that combines functions of separate components of a suspension system of a vehicle into a single unit.
When a vehicle is in motion, the road disturbances encounter by the vehicle input kinetic energy into the passenger cabin of the vehicle and that energy must be dissipated for the comfort of the passenger and any cargo being carried by that vehicle. To dissipate the energy, it is known in the art to employ the use of either shock absorbers or air springs.
U.S. Pat. No. 4,844,428 discloses an air spring assembly wherein the air spring assembly can be adjusted to obtain an optimum spring constant. The air spring is comprised of a shock absorber and a reversible electric motor to vary the spring constant of the air spring. While the disclosed air spring combines many functions, the entire air spring is cumbersome and complex.
U.S. Pat. No. 4,786,035 discloses an air spring with an internal restraint. The air spring is provided with an elongated flexible strap that extends between the end members of the air spring. While this provides the air spring with a means of limited restraint, there is no means for limiting the radial movement of the air spring.
The present invention is directed towards an air spring that combines functions formerly provided by separate components into a single unit. The air spring combines at least two of the following functions: axial spring, lateral stabilizer, jounce bumper, damper, over extension restraint and height control.
The air spring of the present invention is comprised of a flexible airsleeve, a retainer, and a main piston. The airsleeve is secured at one end by the retainer and at the opposing end by the main piston. A hollow restraining piston extends from the retainer and into the main piston. The restraining piston acts as a lateral stabilizer, over extension restraint and height control.
In another aspect of the inventive air spring, the hollow region in the restraining piston communicates through at least one passage with an air chamber formed between the airsleeve and the outer surfaces of the restraining piston and the main piston.
In another aspect of the invention, the air spring is further comprised of a valve. The valve selectively admits or exhausts a fluid from the air spring as a function of the relative displacement of the restraining piston and the main piston.
In another aspect of the air spring, the restraining piston grips an upper portion of the valve to selectively admit or exhaust the fluid. The valve admits fluid into the air spring when the air spring is at a jounce position and the valve exhausts fluid when the air spring is at a rebound position.
In another aspect of the air spring, a pressure chamber is formed between the restraining piston and the main piston. The pressure chamber communicates through at least one passage with the hollow region of the restraining piston. At least one of the passages between the pressure chamber and the hollow interior of the restraining piston being a check valve.